Figure 1.

Schematic to show the experimental design and timeline. The chemogenetic experiments were conducted in adult male and female Long-Evans-Tg(ChAT-Cre)5.1 Deis rats (referred herein as ChAT-Cre rats). The EEG data were recorded continuously, while the microdialysis samples from prefrontal cortex were collected every 12.5 min. Baseline wake data were collected for 50 min, after which the recording chamber was sealed and sevoflurane adminstration (1.7%–2.4%) was started. Respiration and heart rate were then monitored using a rodent pulse oximeter until the end of sevoflurane exposure. After 50 min of sevoflurane anesthesia, compound 21 (C21), the agonist for hM3D(Gq) receptors, was reverse dialyzed for 12.5 min into the basal forebrain of ChAT-Cre rats. Female rats received 0.5 mM C21, while the male rats received 1 mM C21. At the completion of C21 delivery, the rats were maintained at the same sevoflurane concentration until the postsevoflurane recovery epoch. Postsevoflurane recovery data were collected for 50 min. Adult male and female Sprague Dawley rats were used for bilateral electrical stimulation of basal forebrain; electrical stimulation of piriform cortex was conducted to confirm the specificity of response to electrical stimulation of basal forebrain. The experimental design was similar to that followed for chemogenetic experiments except that instead of C21 administration, the rats received electrical stimuli in basal forebrain with or without bilateral infusion of 500 nL of 156 μM TTX into prefrontal cortex. BF indicates basal forebrain; ChAT, choline acetyl transferase; TTX, tetrodotoxin.